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基于热重分析试验和固定床热解试验,研究了升温速率和温度对高矿物质含量的炼焦煤尾煤热解特性的影响。尾煤热解过程可分为室温～400℃、400～600℃及600～950℃3个阶段。采用Coats-Redfern积分法拟合计算了尾煤热解的动力学参数,表明炼焦煤尾煤热解反应过程可以用3个二级反应进行描述,其热解反应活化能介于22.6～66.2 kJ/mol。固定床试验结果表明,温度对尾煤挥发分的析出有重要影响,高温有利于尾煤中高分子有机组成裂解和挥发分析出,最终决定了尾煤的热解反应进程。600℃前气体缓慢析出,之后,随温度升高,气体产量和热值增加显著,H2和CO随温度升高而增加,CH4和CO2先增加后减少。H2在600℃前析出缓慢,600℃后大量析出,在900℃左右达到最大析出量,贯穿整个反应过程。CO在900℃左右达到最大析出量;CH4和CO2在800℃左右达到最大值,之后开始下降。终温950℃时,30 g尾煤热解产气4 300 mL,H2产量1 722mL;焦煤产气7 950mL,H2产量2716mL。尾煤热解富H2体产量达焦煤热解气产量的54%,具有较高的再利用价值。
The effects of heating rate and temperature on the pyrolysis characteristics of coking coal tailings with high mineral content were studied based on TG test and fixed bed pyrolysis test. Coal pyrolysis process can be divided into room temperature ~ 400 ℃, 400 ~ 600 ℃ and 600 ~ 950 ℃ 3 stages. The kinetic parameters of tailings pyrolysis were calculated by Coats-Redfern integral method, which indicated that the pyrolysis reaction of coked coal tailings can be described by three second-order reactions with an activation energy of 22.6 ~ 66.2 kJ / mol. The results of fixed bed experiments show that the temperature has an important influence on the volatilization of the tail coal. The high temperature is beneficial to the pyrolysis and volatilization of the organic components of the tail coal, which ultimately determines the pyrolysis reaction process of the tail coal. Gas slowly precipitated at 600 ℃. Afterwards, the gas yield and calorific value increased significantly with the increase of temperature. The contents of H2 and CO increased with the increase of temperature, while CH4 and CO2 increased first and then decreased. H2 precipitates slowly at 600 ℃, precipitates at 600 ℃, reaches maximum precipitation at about 900 ℃, and runs through the whole reaction process. CO reached the maximum precipitation at about 900 ℃; CH4 and CO2 reached the maximum at about 800 ℃, then began to decline. At the final temperature of 950 ℃, 30 g of pyrolysis gas of 30 g of tailings coal produced 4,300 mL of H2 and 1 722 mL of H2 production; 7,950 mL of coking coal produced gas and 2,716 mL of H2 production. Tail coal pyrolysis rich H2 production reached 54% of coking coal pyrolysis gas production, with high reutilization value.